First off, hope you all had a very merry Christmas and are enjoying the holidays!

My question is regarding a '77 Chevy. I will admit upfront that I know nothing about carb'd vehicles.

Now, for the story...

---------------------------

This past week...

My '77 truck recently began having problems starting and staying on. About a week ago I started it after the usual pumping of the accelerator and it started up with its usual hesitation but then ran just fine. Two days later, it would start but then sputter and die within seconds.

I checked the sparkplug wires that had been replaced only a couple of months ago and, aside from one having its boot practically gone, perhaps from the heat from the exhaust manifold, found no issues.

My immediate assumption was that the fuel pump was failing because the truck has always sounded somewhat starved for fuel. The manager at Autozone suggested checking the points and what not but I doubted that was the case since a tune up had been done about 2 months / 50 miles ago. Besides, flooring the gas pedal always got the truck running every time anyway.

I planned to tackle the job on the weekend.

-------------------------

Saturday morning and afternoon ...

I finally got to work on it this past weekend and had a relative visiting who pointed out that it could be water in the fuel. I didn't think that was the case until he discovered that the fuel cap for the left-side tank was loose. So we put some gas from that tank into a clean container and found it to be whitish clear with some debris floating inside of it and decided that water was indeed the culprit (we've got some Johnny ********* in the area with nothing to do who might've done this).

I tried siphoning the water-contaminated gas out of the left-side tank (it has two) and it didn't work well so I gave up, hoping to use the hose from the sending unit to pump it out later (it was about ready to rain).

----------------------------

Sunday morning, afternoon and early evening ...

Sunday morning, I put some gas into the right-side tank and the truck sputtered a bit before starting and staying on just fine. As soon as I would switch over to the left-side tank, it would sputter and die. So I thought, "Problem found."

I went to AutoZone, bought a locking fuel cap (they only had one in stock) and bottle of Iso-heet to clean the water out of the fuel lines and tank. I poured the bottle into the left-side tank and locked it with the new cap.

I then tried locating the hose from the left-side tank to pump out the bad gas using the sending unit but gave up after a while because I just couldnít seem to find the right one and it was getting dark.

I then made two trips to the gas station and bought a total of four gallons of gas to put into the right-side tank so I could at least move the truck around for a while as needed (street sweep is Tuesday).

After putting the gas into the tank, I started it up and let warm up for quite a few minutes. The truck did so without any issues. I decided to drive it around a bit to make sure all was well. It took off perfectly.

I noticed the hood was still unlocked. As I pulled over to close it, the truck began sputtering again and died. After that, it just would not start.

I popped the hood and, after removing the air filter assembly, found white smoke coming from the carburetor. The glass-cased fuel filter seemed full of gas. My immediate thought was "flooding" or "vapor lock". I also found that a vacuum hose was still off of the carburetor from working on the fuel line earlier and the smoke was coming out of that as well (looked more like thick steam, to be fair).

I googled flooding and vapor lock and found some info. Went back to the truck after about half an hour, tried starting it again and nothing. This time, I noticed the fuel filter case was barely half full.

I am about to head out and try starting it again. Iím going to take off the gas cap, stick a screw driver in the carb's flap and see what happens.

----------------------------

Sunday, 8:45 pm PST

So I did some thinking on the way to the truck.

I did a tune up on the truck with a buddy about two months / 50 miles ago (sparkplug, wires, cap, rotor, ignition coil, air filter). Afterwards, I noticed that it backfired a lot at 65 mph or higher. It really didn't like going past 55 mph. I assumed a sparkplug wire must've slipped off or something. After checking it a few days later, I found one to be loose and pushed it in place. Never had a chance to get back on the freeway (I hardly ever drive this thing) but noticed that when I would rev it while parked, it would still backfire. I also noticed that the truck still got the same gas mileage as before: 10 mpg.

While researching what might've happened to my truck earlier today, I saw a post that mentioned that sparkplugs can be gapped and timing can be messed with in a way to hide a carburetor's problems (carb itself doesn't seem to have a manufacturer's name visibily marked could it be a generic / Q-Jet deal?). I can't help but wonder if that is what is causing the back fire and lack of power. I mean only 55 mph? C'mon ...

So I got to the truck and, after checking the radiator, unlocking the fuel cap and sticking a screwdriver in the carb's flap, it started just fine. After letting it run for about a minute and a half, I drove it back home. During the drive, the acceleration seemed fine, better than before even. So I thought I'd run it a little longer by making a couple more runs up and down the street.

Once I brought it home and got ready to park, the truck began losing power and the idle dropped very very low, but not to the point of sputtering. I checked the temperature and it was at only 160 degrees. I turned it off and started it back up and it did so immediately, but the idle was still very low.

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Monday, 8:15 am PST

I started the truck this morning and, after a few seconds of low idling, it died. So I started it again and it kept idling very low (showed under 500 rpm on the cheapo after-market tach), but it didn't shut off this time. I let it run like that for a few minutes and then revved the truck a couple of times to about 2500 rpm, after which it would settle down to about a 1000 rpm at idle (where it normally idles, even during cold starts). I imagine the idle itself needs to be adjusted and need to look up how to do it.

Any thoughts?

Thanks in advance...

kukamojo

12-27-2010 02:41 PM

Does the truck have an electric or manual choke?

Did you set the timing with a light at 800 rpm with the vacuum disconnected and also set the "all-in" timing?

It sounds to me like you have a timing issue, combined with a potentially faulty choke mechanism. If the choke is pulling shut, the motor will lose power and eventually flood out. Also, if the choke is not correctly set at first start up, the fast idle cam will not be engaged, which would explain 500 rpm until you got warmed up.

Make sure the plugs are gapped correctly, as you had mentioned it above. Also, if you have a points distributor you should check the points gap as well as dwell. If these are incorrect it will affect the timing.

So... set the timing correctly. Get the engine up to temp and check with a timing light. (assuming your timiing marks are correct). At 800 rpm vacuum disconnected it should be somewhere between 8-12 degrees BTDC. Then check the all in with vac disconnected. It should reach all-in by 3000 RPM and be somewhere the mid 30's BTDC.

... once you have eliminated timing as the issue, check the choke operation at dead cold vs running temperature.

T-bucket23

12-27-2010 03:44 PM

Try it without the gas cap, may be the wrong type of venting for your fuel system. It would have seemed you found the issue with the dirty fuel. When you changed all the ignition parts, did you gap the plugs and if it is a points style ignition, how did you set them. If the fuel had so much crap in it that you could see it, a bottle of dry gas is not going to solve that issue, you need to drain that tank. Until you can do that continue to run off the good tank.

cyclopsblown34

12-27-2010 04:11 PM

If the coil is integral with the cap, it isn't points. It should have an HEI distributor. If it has points, you need a resistor wire in line so as to not fry the points. I'm leaning towards the choke though since you said with the choke blocked open it started right up.

lt1silverhawk

12-27-2010 04:28 PM

Hey kukamojo,

Quote:

Originally Posted by kukamojo

Does the truck have an electric or manual choke?

I'm 99% certain it is a manual choke (I didn't see any wires running to it).

Quote:

Originally Posted by kukamojo

Did you set the timing with a light at 800 rpm with the vacuum disconnected and also set the "all-in" timing?

Actually, I never messed with thwe timing at all. I have never done anything related to timing so this will be a first for me.

Quote:

Originally Posted by kukamojo

It sounds to me like you have a timing issue, combined with a potentially faulty choke mechanism. If the choke is pulling shut, the motor will lose power and eventually flood out. Also, if the choke is not correctly set at first start up, the fast idle cam will not be engaged, which would explain 500 rpm until you got warmed up.

Based on what I've read up on in the past 24 hours, I'm starting to believe timing is an issue. I now have some reading to do on the choke and how to adjust it.

Quote:

Originally Posted by kukamojo

Make sure the plugs are gapped correctly, as you had mentioned it above. Also, if you have a points distributor you should check the points gap as well as dwell. If these are incorrect it will affect the timing.

My friend did the sparkplugs and while I am 100% confident he gapped 'em to stock specs (0.060" for california vehicles according to the AutoZone site), I will recheck each one again.

Quote:

Originally Posted by kukamojo

So... set the timing correctly. Get the engine up to temp and check with a timing light. (assuming your timiing marks are correct). At 800 rpm vacuum disconnected it should be somewhere between 8-12 degrees BTDC. Then check the all in with vac disconnected. It should reach all-in by 3000 RPM and be somewhere the mid 30's BTDC.

... once you have eliminated timing as the issue, check the choke operation at dead cold vs running temperature.

Due to work, my lack of knowledge and the lighting available, I will have to do this some time this weekend.

Thank you so much for the pointers! :D

lt1silverhawk

12-27-2010 04:51 PM

Hey T-bucket123

Quote:

Originally Posted by T-bucket23

Try it without the gas cap, may be the wrong type of venting for your fuel system. It would have seemed you found the issue with the dirty fuel.

Yes, I was hoping the contaminated gas would be the only issue.

I was thinking it may be the gas cap as well. It is of a different material and doesn't seem to have any form of pressure release/ventilation.

Quote:

Originally Posted by T-bucket23

When you changed all the ignition parts, did you gap the plugs and if it is a points style ignition, how did you set them.

I honestly can't recall how I set the points but the sparkplugs were gapped to 0.060".

Quote:

Originally Posted by T-bucket123

If the fuel had so much crap in it that you could see it, a bottle of dry gas is not going to solve that issue, you need to drain that tank. Until you can do that continue to run off the good tank.

Right, the draining turned out to be a bigger hassle than expected. As soon as I can locate the hose from that tank's sending unit, it's all coming out. (Half tank's worth :(

Thanks T-bucket123! :D

lt1silverhawk

12-27-2010 04:54 PM

Hey cyclopsblown34,

Quote:

Originally Posted by cyclopsblown34

If the coil is integral with the cap, it isn't points. It should have an HEI distributor. If it has points, you need a resistor wire in line so as to not fry the points.

The coil is integrated with the cap, that I do remember. Guess I didn't touch the points since they weren't there... :confused: ... Maybe its the ignition control module I'm thinking of...

Quote:

Originally Posted by CYCLOPSBLOWN34

I'm leaning towards the choke though since you said with the choke blocked open it started right up.

Yep, that seems alikely cuplrit based on the responses from you guys.

Now, to research on how to fix it...

Thanks cyclopsblown34! :D

lt1silverhawk

12-27-2010 05:34 PM

Does it matter if the engine is a crate 350 from Goodwrench? I ask this in regards to proper gapping of sparkplugs.

1971BB427

12-27-2010 07:24 PM

Just a thought; but did you check the fuel filter(s)? There should be one inline between the tank(s) and the carb, but also a sintered bronze filter that is built into the inlet of all Q jet carbs. You need to pull the inlet off to remove that filter, and when you do just toss it away. Better to use a really good inline ahead of the carb.
With all the dirty fuel problems you've had, I'd sure expect the filters to be plugged.

lt1silverhawk

12-27-2010 07:31 PM

Hey 1971BB427,

Quote:

Originally Posted by 1971BB427

Just a thought; but did you check the fuel filter(s)? There should be one inline between the tank(s) and the carb, but also a sintered bronze filter that is built into the inlet of all Q jet carbs. You need to pull the inlet off to remove that filter, and when you do just toss it away. Better to use a really good inline ahead of the carb.
With all the dirty fuel problems you've had, I'd sure expect the filters to be plugged.

Good suggestion!

There is a glass-cased inline filter right before the carb (8 inches of hose between them).

While digging for the hose from the left-side tank's sending unit, I also found two more metal inline filters by the right-side tank. Cleaned out the glass-cased filter but havent touched the other two yet. I will replace all three of them asap.

As for the one built into the inlet of the carb, I didn't see one but will check for it.

Thanks for the help! :thumbup:

lt1silverhawk

12-28-2010 01:06 AM

UPDATE: Monday, 9 pm.

Came home and started the truck and it died again instead of staying on like last night and this morning.

I went to AutoZone and picked up the second gas cap, along with two new fuel filters that I'll be replacing tomorrow morning.

The family decided that we should move the truck into the drive way tonight so we have no issues tomorrow morning for street sweep. The damn thing died again many times on the climb (it is a rather steep angle and very narrow as well). Again, more smoke/steam from the carb. It was all blamed on flooding and that I may have installed the glass-cased fuel filter right before the carb backwards. So I swapped it and tried again, but no luck.

Finally, the battery died.

Put the battery on charge, bought another two gallons of gas and put it in the right-side tank (the clean one). Stuck a screwdriver in the choke plate, unscrewed the gas cap, sprayed some starting fluid directly into the plate, put the battery back on and it puttered to life.

After restarting the truck a million times while moving it up and down the incline to get it straightened out, I finally parked it were it died last.

And so the quality family time ended with that.

One of the things I need to look into is how to adjust the choke. It is a mechanical choke but I didn't see a cable/knob inside the cab for it. Something else to work on tomorrow.

Lets see what tomorrow brings...

T-bucket23

12-28-2010 08:33 AM

Quote:

Originally Posted by cyclopsblown34

If the coil is integral with the cap, it isn't points. It should have an HEI distributor. If it has points, you need a resistor wire in line so as to not fry the points. I'm leaning towards the choke though since you said with the choke blocked open it started right up.

I didnt see where he said the coil was in the cap.
It does hoever sond more and more like a choke or fast idle cam issue

cyclopsblown34

12-28-2010 08:53 AM

Quote:

Originally Posted by T-bucket23

I didnt see where he said the coil was in the cap.
It does hoever sond more and more like a choke or fast idle cam issue

Being a 77, it should have HEI which he confirmed. I think HEI came into being as standard on GM stuff in 73 or 74.

To adjust the choke, if it is a Quadrajet, there is a canister on the lefthand side of the carburetor, it might have three screws or rivets holding it in place. Hopefully it has the screws, you back them off and rotate the canister in the direction of the arrow pointing to lean, in absence of the canister being marked lean, rotate the canister til the choke opens up and then tighten the screws down to hold it in place, try starting it then. Once it starts pretty regularly, you should be able to adjust the idle mixture screws on the carburetor at the base on the front, they are two screws pretty well hidden from view and have springs on them to help hold their position. Turn them in gently to bottom out, do not crank them down, then back them both out 2 full turns and try to start the truck. You can then adjust each screw 1/2 turn and see how it idles then.
You might want to tighten up the plug gap too, .045 is what I've always gapped plugs on HEI systems at, unless it had a hot aftermarket coil. There is also the possiblity you could have croseed two plug wires but that usually results in a backfire.

cyclopsblown34

12-28-2010 09:43 AM

I cannot believe I typed lefthand, it should be right hand/passenger side of the carburetor.

T-bucket23

12-28-2010 10:21 AM

Quote:

Originally Posted by cyclopsblown34

Being a 77, it should have HEI which he confirmed. I think HEI came into being as standard on GM stuff in 73 or 74.

To adjust the choke, if it is a Quadrajet, there is a canister on the lefthand side of the carburetor, it might have three screws or rivets holding it in place. Hopefully it has the screws, you back them off and rotate the canister in the direction of the arrow pointing to lean, in absence of the canister being marked lean, rotate the canister til the choke opens up and then tighten the screws down to hold it in place, try starting it then. Once it starts pretty regularly, you should be able to adjust the idle mixture screws on the carburetor at the base on the front, they are two screws pretty well hidden from view and have springs on them to help hold their position. Turn them in gently to bottom out, do not crank them down, then back them both out 2 full turns and try to start the truck. You can then adjust each screw 1/2 turn and see how it idles then.
You might want to tighten up the plug gap too, .045 is what I've always gapped plugs on HEI systems at, unless it had a hot aftermarket coil. There is also the possiblity you could have croseed two plug wires but that usually results in a backfire.

Yup, hei started in 74 in limited production, by 75 it was in everything.
Cadillac may have had some in 73